Mechanics

LOW BRAKE PEDAL

2000 Dodge Van

Brakes problem
2000 Dodge Van V8 Two Wheel Drive Automatic 190000 miles

I have a truck with a low brake pedal problem. I have bled the system, the front brakes pads and rear shoes are good. IO changed the master cylinder as well in the truck. The pedal is very soft and low when I try to use the brakes but there are no leaks anywhere. The pressure when I bleed the system is very good. The truck has no brake light on either. I am at my wits end trying to figure this out. There is a proportioning valve that has a little needle that comes out a little when the brake is applied and that, according to the manual, is the test that that part is good.
Avatar
Paisturbo
January 15, 2010.




Check the rear adjusters, if frozen the pedal will gradually go lower, as the brakes are not adjusting, common problem. Remove the drums and check/adjust rear brakes, these control pedal height!
Test by setting the parking brake, if pedal is good, rears are out of adjustment. The other possibilty is you got air in the ABS(HCU), this requires a Crhysler capable scantool to bleed the HCU.
BLEEDING HYDRAULIC CONTROL UNIT (HCU) 1. Bleed base brake system using manual or pressure bleeding procedure. See MANUAL BLEEDING or PRESSURE BLEEDING. 2. Connect scan tool to Data Link Connector (DLC) located under left side of instrument panel. See Fig. 4 or Fig. 5. Using scan tool, check for stored Diagnostic Trouble Codes (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES under DIAGNOSTIC PROCEDURE. If no DTCs exist, go to next step. If DTCs exist, clear DTCs from Controller Anti-Lock Brake (CAB) using scan tool, and bleed base brake system using manual or pressure bleeding procedure. See MANUAL BLEEDING or PRESSURE BLEEDING. Go to next step. 3. Using scan tool, perform ABS bleeding procedure. Follow screen prompts to bleed brake system. Disconnect scan tool. Bleed base brake system again using manual or pressure bleeding procedure. Go to next step. 4. Fill master cylinder with brake fluid (if necessary). Repeat bleeding procedure until brake fluid flow is clear and free of bubbles. Test drive vehicle to ensure brakes operate properly and brake pedal is not spongy. CAUTION: Ensure manual bleeding or pressure bleeding procedure is performed before bleeding Hydraulic Control Unit (HCU).
Bleed system in this order, adjust rears, then if still low, get the scantool! Here's the bleeding sequence.
BRAKE SYSTEM BLEEDING Bleed only one brake component at a time in the following sequence: Master Cylinder Combination Valve Rear Anti-lock Valve Right Rear Wheel Left Rear Wheel Right Front Wheel Left Front Wheel Manual Bleeding 1. Remove reservoir filler caps and fill reservoir. 2. If calipers, or wheel cylinders were overhauled, open all caliper and wheel cylinder bleed screws. Then close each bleed screw as fluid starts to drip from it. Top off master cylinder reservoir once more before proceeding. 3. Attach one end of bleed hose to bleed screw and insert opposite end in glass container partially filled with brake fluid. See Fig. 5. 4. Open bleeder, then have a helper press down the brake pedal. Once the pedal is down, close the bleeder. Repeat bleeding until fluid stream is clear and free of bubbles. Then move to the next wheel. Fig. 5: Bleeding Brake System Courtesy of CHRYSLER CORP. WARNING: DO NOT pump the brake pedal at any time while bleeding. Air in the system will be compressed into small bubbles that are distributed throughout the hydraulic system. This will make additional bleeding operations necessary. WARNING: DO NOT allow the master cylinder to run out of fluid during bleed operations. An empty cylinder will allow additional air to be drawn into the system. Check the cylinder fluid level frequently and add fluid as needed. NOTE: Use Mopar brake fluid, or an equivalent quality fluid meeting SAE J1703-F and DOT 3 standards only. Use fresh, clean fluid from a sealed container at all times. NOTE: Be sure end of bleed hose is immersed in fluid.
1/15/2010 .

Merlin2021
Jan 15, 2010.


AD